Ethylene-containing polymeric materials possess suitable electrical insulating properties for many known types of electronic devices and applications. However, for electrical devices, connectors and conductors operating with very low electrical currents, it becomes extremely critical to provide the maximum amount of insulation and effectively prevent even very low levels of electrical current leakage or loss. This is particularly important for modules comprising one or more low-current electronic devices including, but not limited to, solar cells (also known as photovoltaic cells), liquid crystal panels, electro-luminescent devices and plasma display units. The modules often comprise the electronic device in combination with one or more substrates that provide protection and or support for their manufacture, transportation, and use. For example, these types of devices are frequently positioned behind one or more glass cover sheets and/or between two substrates in which one or both of the substrates comprise glass, metal, plastic, rubber or another material. In these cases, polymeric materials are typically used as an encapsulant or sealant for the device within the module or, depending upon the design of the module, directly as a covering or skin layer component of the module, e.g., a backskin in a solar cell module.
United States Patent Application Publication 2001/0045229 A1 identifies a number of properties desirable in any polymeric material that is intended for use in the construction of an electronic device module. These properties include (i) protecting the device from exposure to the outside environment, e.g., moisture and air, particularly over long periods of time (ii) protecting against mechanical shock, (iii) strong adhesion to the electronic device and substrates, (iv) easy processing, including sealing, (v) good transparency, particularly in applications in which light or other electromagnetic radiation is important, e.g., solar cell modules, (vi) short cure times with protection of the electronic device from mechanical stress resulting from polymer shrinkage during cure, (vii) high electrical resistance with little, if any, electrical conductance, and (viii) low cost.
WO20111/53541A1 discloses desirable electronic device module encapsulation films which are based upon an interpolymer of ethylene and at least one alpha-olefin having, an overall polymer density of not more than 0.905 g/cm3, a relatively low total amount of unsaturation, and a relatively high ratio of vinyl groups to total unsaturated groups in the polymer chain, and prepared in a solution-polymerization process using a polymerization catalyst that is a metal complex of a polyvalent aryloxyether of a specific type. For the example polymers, the catalysts were supplemented and activated by cocatalysts bis(hydrogenated tallow alkyl)methyl-ammonium, tetrakis(pentafluorophenyl)borate and MMAO (modified methyl aluminoxane).
In US 2010/0036069A it is noted that in the production of ethylene polymers, certain cocatalysts can provide a decrease in the electrical charge dissipation factor.
It would be desired to provide improved polymeric materials and polymeric material structures suitable for use in low current electrical device uses and providing better combinations of performance in the physical, optical and electrical properties. In particular, in electronic devices, such as photovoltaic modules, it would be desirable to provide improved efficiency in insulation and, in turn, improve conductance in the electronic device. For example, in the case of photovoltaic modules, this would desirably maximize recovery of the current generated for subsequent use or storage.